Warranty claim process and replacement questions?

So I ordered the purple 3 back in 2019. Have a little bit of sagging or indentation ? Not bad but noticeable if I lay on the other side definitely more firm. If I do the warranty do they still make the purple 3? Or would I have to pay extra for whatever model they currently have? And for getting rid of the old one do they pickup or can I just take it to a homeless shelter or something? Just cause it’s not bad at all for someone who needs it but definitely noticeable difference compared to new and also to the opposite end and would rather replace it under warranty